1. Field of the Invention
This invention relates to pipelines and has particular reference to pipelines for transporting congealable fluids.
The term "congealable fluid" as used herein means a fluid which, as a result of changes in temperature, pressure, flow, or degradation can result in the formation of a substantially solid, substantially unmoveable product.
The invention has particular application to congealable fluids susceptible to exothermic reactions, such as congealable pastes or slurries. The invention has further particular application to pipelines for the transport of mixtures of cellulose, a tertiary amine n-oxide and a non-solvent for cellulose, such as water.
2. Brief Description of the Prior Art
It is well known to incorporate into pressure vessels a safety pressure relief device. A common form of safety pressure relief device is a bursting disc. A bursting disc essentially comprises a membrane which is relieved--either by bursting open or being blown out of its holder, or both, under the action of a pressure greater than the normal operating pressure for the pressure vessel but below the pressure at which the vessel itself will rupture.
Bursting discs are conventionally mounted in small pipe spurs located off of a pressure vessel or are formed as part of the wall(s) of the pressure vessel.
It has now been discovered that there may be particular problems with pipelines for transporting a congealable fluid where an excess pressure may arise in the transport pipeline itself. The present invention is concerned with the provision of an over-pressure device for a pipeline for transporting a congealable fluid where there is a possibility that an excess pressure may arise within the congealable fluid. The excess pressure may arise within the pipeline itself or may be the result of a rise in pressure external to the pipeline.